Stiffened material



March 20, D E. GILLUM ET AL STTFFENED MATERIAL` Filed April `2.2, 1942 2Sheets-Sheet l i k A j W y L *J 12 WIG.

Y C: [i672 2f j ,mg Rf@ March 2o, 1945. D. E GILLUM ETA'L 2,371,754`

l STFFENED MATERIAL. l

Filed April 22, 1942 2 Sheets-Sheet 2 ATTORNEY partV of the skin of anairplane.

Patented Mar. 20, 194.5

STIFFENED MATERIAL t Donald E. Gillum, vHermosa Beach, and Dale .I

Van Riper, Los Angeles, Calif., assignors to North American Aviation,Calif., a corporation o! Delaware Inc., Inglewood,

Application April 22, 1942,`Seral No. 440,040 6 claims. (ci. 18o-34') inaircraft, automobiles, railroad cars, and alll other fabricated articlesor machines embodying a surface or similar part thereof that is subjectto vibration or bending inuences.

Further objects reside in the provision of a material that is easilyfabricated, relatively inexpensive to manufacture, easily used inassembling other articles, serviceable and of. general superiority. v

The following description merely, describes and the accompanyingdrawings merely show embodiments or suggested forms, and are not to betaken. as the only possible embodiments or forms.

' In the drawings, like reference characters designate similar parts inthe several views.

Fig. 1 is a perspective `view of material made in accordance with thepresent invention employed, as a leading edge of an airplane Wing.

Fig. 2 is a plan view of a portion of such material, broken away.`

Fig. 3 is an enlarged section taken on the line 3 3 of Fig. 2.

Fig. 4 is an enlarged section taken on the line 4 4 of Fig. 2.

Fig. 5 is a view similar to Fig, 4, but showing a modiiied construction.

Figs. 6 to 13 are plan views of modied arrangements of the stileningmeans.

Fig. 14 is a sectional view taken along the line Ill-I4 of Fig. 11,showing a still different cross sectional shape for the wire.

Referring more in detail to the drawings, the reference numberI I2generally designates the sheet material, which in Fig. 1 is shown as theThe sheet materialY I2 may be of steel, aluminum, etc. `In Fig. 1,stringers or strengthening members I3 are suggested, for reenforcing thewing I4.

Irib l5 is also indicated in that figure.

The stiiening means for the sheet material I2 is preferably wire, but itmay be of any desired arrangement of wire running in directions atangles toeach other. The wire may also be in the form of a mesh.

In Sheet I of the drawings, the wires are shown A bracing formingrectangles and extend substantially parallel with the sides and ends ofthe sheet material. It is believed-clear that the present stifenedmaterial may be formed by-any of the following processes: seam welding,spot welding, brazing, cementing, are welding, or the like.

Spot welding has been suggested in Figs. 2 to 4. Spot welding may ofcourse be-v done by any suitable gang or gangs of spot weldingelectrodes. A suggested apparatus has been illustrated in our pendingapplication fi, 1942.

Longitudinal wires I6 are crossed by transverse wires Il on the back ofthe sheet material I2. Upon thepoint of the crossing over of one wire byanother sufilcient heat and pressure are apl plied by the weldingelectrode to cause the two Fig. 5 illustratesgwires 20 of modied cross-lsection, to wit, rectangular. The rectangular wires 20 are weldedtogether at their intersections and Welded to the sheet metal I2 atsuch, intersections, just as the round wire.

Fig. 6 shows tubular wires 2 I, which are utilized the same as theround, solid wires hereinbefore described.` The tubular wires stillfurther lower the weight-stiffness ratio of the nished material.

Fig. '7 illustrates solid wires 22 of irregular cross.

section. Converging flat sides 23 increase the resistance of the wires22 to bending. Thetop I9 of the wires 22 may be nat, while the curvedbottom may be fused to the sheet material I2. Although there is the sameamount of metal in the wire 22 as in a round wire having a diameterequal to the lower, curved portion of the `wire 22, the cross section ofthe wire 22 has aconsiderably higher neutral axis than the neutral axisof round wire having a diameter equalg'to the lower, curved portion ofwire 22. The wire 22, therefore, has more stiines's than round wirehaving the same amount of material.

Fig. 8 shows metal rings 24 that are simultaneously welded to each otherand to the sheet material, as suggested at 25.

Fig. 9 illustrates ellipses 26 with smaller rings 21 connecting rows ofthe ellipses with each other.

Serial No. 445,822, led June I `This arrangement of ellipses and ringsmay be prefabricated and such prefabricated arrangement welded upon aface of .the sheet material l2 for strengthening purposes. It will benoted that there are considerably more wires crossed by the broken line34 than by the broken line 35,

thus the direction of greatest rigidity can be controlled, for there isgreater resistance to bending along the line 34 than along the line 35.By this arrangement, the sheet material is stiilened in one directionmore than the other.

Fig. shows series of rosettes 28 which may be Prefabricated and suchprefabrication layed upon the sheet l2 and welded in place.

Fig. l1 is similar to the arrangement shown in Figs. 1 and 2, butshowing a diagonal arrangement of wires 29 upon the sheet I2. l

Fig. 12 shows angularly bent wires 30 that are layed adjacent each otherand welded in place upon the sheet material I2. This arrangement can beused to control the direction of greatest rigidity as in the case of theform in Fig. 9.

Fig. 13 shows a hexagonal form 3l that is prefabricated andthen appliedto the sheet I2 and welded in place.

Fig. 14 shows a modified I-beam construction that may be used for thewires. This gure is taken along theline H-I'l of Fig. 11.

It is to be understood that the `word Wmr in the present description andinthe hereunto appended claims shall include both drawn material andextruded material and differentcross sectional shapes, and shall includeboth solid and hollow forms. Moreover, ,welded shall be taken to includenot only spot and seam welding which comprises joining together byfusing abutting surfaces with or without the addition of extra metal,but also brazing, cementing and arc welding.

Any of our present materials may be produced by mass production methods,and such material have many uses in the fabrication of aircraft,

automobiles, railroad cars, etc.

While we have illustrated and described what l claim and desire tosecure by Letters Patent is:-

1. An article of manufacture comprising a section of sheet metalpresenting a continuously un` broken surface at one side thereof, and areenforcing and vibration reducing web of wire elements on the othersurface thereof, said elements being in individually complete units of aclosed. .curved shape in plan view and presenting Contlnuously curvedperimeters, integrally joined to one another and to the sheet metalsurface at spaced points along the perimeters thereof.

2. As an article of manufacture, a skin covering for vairplanes andairships, consisting of a single layer of sheet metal presenting anexternal unbroken surface, and reenforcing wire elements in individuallycomplete geometrical units of a closed, curved shape in plan view anddisposed with their perimeters in touching relation and welded to oneanother and to the other surface of the plate at said touching points.

3. An article of manufacture, consisting of sheet metal, and reenforcingwire elements disposed against a surface of said sheet metal inindividually complete units of a closed, curved shape in plan view andpresenting curved perimeters in touching relation at spaced pointstherearound, and substantially integrally joined at said spaced touchingpoints to one another and to the sheet metal. f

4. An article of manufacture, consisting of sheet metal, and a surfacelayer of peripherally touching individually complete wire elements inindividually complete units, said units being of closed, curved shape inplan view and being alternately of ovate and circular form in successiverows, the circular units being disposed between the smaller ends of theovate units, and all of said units being substantially integrally joinedto one another and to the sheet metal at the points of touching of theunits.

5. An article of manufacture comprising a sheet metal layer andreenforcing elements consisting of L wire-like ribs presenting crosssectionally thereof rounded basal edges substantially integrally joinedto and across a surface of said sheet metal layer, and straight sideedges converging from said rounded basal edge to a free edge.

6. An article of' manufacture comprising a sheet metal member, and wiresarranged in individually complete, and elongated units of a closedcurved shape in plan view, and disposed on the metal member with theelongations extending substantially in the same direction on the sheetVmetal member to provide greater resistance to bending on a linetransverse to the elongations than parallel with the elongations, andthe wires being substantially integrally joined. to one another and tothe sheet metal member at a side thereof.

`DONALD- E. GILLUM. DALE H.v VAN RIPER.

